A Language Design Developer creates and modifies programming languages, focusing on the syntax, semantics, and pragmatics of the language. They analyze user needs, develop language features, and define the rules for language structure and usage. They work on the translation of programming languages into machine-readable code, and also manage debugging and problem-solving related to the language design. They often collaborate with software developers to ensure the language meets their needs and facilitates efficient coding. Their role also involves staying updated with latest trends in language design, and enhancing the language to incorporate new features.